in order to crease a storage capacity of a hard disc drive (HDD), there is a need to record signals in a microscale region of a disc. For the purpose of writing signals in the microscale region of a disc while assuring the stability of the recorded signals in the presence of thermal changes, it is necessary to use a thermally stable recording medium. This however poses a dilemma in that strong magnetic fields are required to rewrite the signals. Nowadays, the recording density grows saturated in an up-to-date GMR (Giant Magneto Resistance) method. Thus, there is a need for a “heat-assisted recording” method.